Process of obtaining porous and fairly-pure barium oxid from barium carbonate.



- erable diiiiculty,

KARL BGRNEMANN, AIX-LA-OHAEELLE, GERMANY, ASSIGNOR TO- CHEMISCHE FABBIK COSWIG-ANH'ALT, G. M. B. H., OF

PRQCESS 0E OBTAINING POROUS AND FAIR-LY-IPURE BARIUM GARBUNATE;

COSWIG-ANHALT, GERMANY.

0X11) FROM Barnum i,(lt1,583. No Drawing.

To all whom ttmayconcern:

Be it known that I, KARL BORNEMANN, a citizen of the Empire. of Germany, and re siding at Aix-la-Chapelle, Germany, have invented a certain new and useful 1111- proved Process of Obtaining Porous and Fairly-Pure Barium Oxid from Barium Carbonate, of which the following is a specification.

My invention relates to a process of obtaining porous and fairly pure barium oxid from barium carbonate.

The manufacture of barium, oxid which is simultaneously fairly pure, porous and readily convertible into baric peroxid, from barium carbonate is connected with considbecause under the conditions which generally prevailthe decomposition can be brought about only at temperatures at which the reaction mass tends to be largely converted into a highly sintered and, indeed, partially molten condition. Now I have found that these difficulties can be very largely obviated when the tempera ture of decomposition of mixtures of barium carbonate and suitable reducing agents, specially carbon, is diminished by causing these mixtures to react not at an ordinary pressure as heretofore, but at re duced pressures which means. For example, whereas in my tests at atmospheric pressure, the reaction took place fairly completely only at approx. 1100 0., it could be brought about completely at a pressure of 10-20 mmuinercury at.860 0., and at a pressure of 6570 mm.

. mercury at 940970 (3., to mention only two extreme examples. atmospheric pressure was highly sintered, indeed partially molten, whereas the tests of oxid obtained at the reduced pressure had the formof a very fine powder only loosely caked together. Simultaneous tests for converting-the oxid obtained into baric pcroxid yielded, for example, in the case of the oxid produced at a pressure of 65-70 mm. mercury, a peroxid containing 87%.'barium' dioxid (BaO in spite of the tests being carried out in a very primitive manner without stirring or other movement of the oxid, Whereas the oxid which was otherwise treated exactly similarly but produced at atmospheric pressure yielded a peroxid coni Specification of Letters Patent. Application filed July 31, 1912. Serial No. ?12,573.

can be readily ob tained technically with simple auxiliary Theoxid made atv b Patented oer. ia'ioie.

taining on an average only .-i7% barium dioxid (13210,). I may add that even materially less diminution of that employed. in the mentioned examples distinctly shows the efi ect; the greater the reductionof the pressure, the more favorable, it is true, is the action. But as, on the other hand, a great diminution of pressure is, in general, connected with greater expenseythe pressures to be maintained will vary according to the met with in each case. by the pressure having stances to be materially phere.

hen technically carrying into practice the process resulting from these observa tions I proceed, for example, as follows One ormore vessels of flat, muffle-shaped, cylindrical or other suitable form offireproof material which not only reacts as little as possible with barium oxid and is used for containing the reduction mass but can also be electrically heated by a resistance, 6. 9., spirals of iron, nickel or carbon, wound is or are built into a larger A limit is, set only under all circumless than 1 atmosoutside it, vessel or container of strong sheet-iron, 6.9., boiler piates riveted air-tight together, or other material impervious to air and sufl'iciently able to withstand the pressure of the outer atmosphere. This larger vessel or container, whose Walls may be covered within, tion to avoid losses of heat, is so arranged that all its apertures, such as for doors, holes for electric conductors to the resist. ances, and the like, can be closed airtight, so that the entire container can be evacuated y means of an air-pump to a very low pressure. After this furnace has been charged with the reaction mass, 6. 9., barium carbonate and charcoal, it is evacuated to the desired pressure materially pheric, and the reaction chamber is heated by means of the electric current to a temperature at which the reaction becomes vigorous and continues to the end, the reaction gases being, of course, constantly drawn 0E in order to maintain'the low pressure. The barium oxid which is .formed can then be drawn ofi' while hot and the still hot fun nace can be charged afresh, and so on.

1 As the process is connected with consid- 1 erable generation of gas, the course or end pressure than.

below atmospractical conditions if. desired, with a refractory insulaof the reaction is shown by the degree of this generation of gas or by'its termination. The development of gas is indicated at the manometer connected to the furnace owing to the pressure rising a few millimeters, but of course it may be measured in any other desired manner.

1. A process of producing very porous, fairly pure' barium oxid from barium carbonate, consisting in heating a mixture of barium carbonate and a reducing agent to the reaction temperature at a pressure below atmospheric.

2. A process of producing very porous, fairly pure barium oxid from barium carbonate, consisting in heating a mixture of barium carbonate and a reducing agent in a partial vacuum to the reaction temperature of the mixture, and in constantly drawing ofl the gases which are produced.

In testimony whereof, I afiix my signature in the presence of two witnesses.

KARI BORNEMANN.

Witnesses HENRY CUNAIING, ELISE KALBUSGH. 

